This invention relates to absorbent nether garment liners such as sanitary napkins and panty shields and more specifically, to such products which employ adhesive means for attaching the product to the crotch portion of a nether garment when in use. Such products are provided to absorb and retain body fluids and to protect the nether garment from staining and soiling. The prior art is now replete with suggestions for absorbent liners comprising an absorbent body having garment and body contacting major surfaces and provided with pressure sensitive adhesive means on the garment contacting surface for adherence of the product to a nether garment. Generally, these liners are provided with a protective release strip overlying the pressure sensitive adhesive element and protecting it from dirt and unintentional adhesion when packaged, stored and handled prior to use. At the time of use, the strip is peeled from the adhesive means and the product is positioned and adhered to the undergarment. After use, the product is peeled from the undergarment and disposed of.
The adhesive system employed in such products must meet several sometimes conflicting criteria. In use, it is important that the product adhere tenaciously to the undergarment at all times and so the adhesive system must resist moisture, the sudden torques exerted by movements of the body and the frictional shearing forces exerted by the movements of the various layers of clothing worn by the user. Notwithstanding the adherence tenacity required of the adhesive system during use, it is important tha the protective strip be easily peeled from the adhesive prior to use without tearing or delaminating the product. After use, it is essential that the product be easily peeled from the undergarment, again without tearing or delaminating the product or, in this case, without doing damage to the fabric of the undergarment. In view of the fact that after use, the product is generally soiled, it is important that the user can easily and quickly grip the product and peel it from the garment without undue fumbling or effort.
Several solutions have been offered to this problem of providing in-use tenacity in combination with facile peelability. For example, in U.S. Pat. No. 3,897,783, issued to J. A. Ginocchio on Aug. 5, 1975, the adhesive element provided therein terminated in peaks which resulted in a decreased peeling force at the peaked terminal portions. This adhesive pattern was applied by employing a specifically designed adhesive applier. While this solution is generally effective, it suffers from the drawback of requiring intermittent application of adhesive, it is generally preferred in high speed operations to perform such a step continuously.
Still another solution to the problem is to provide a product with a so-called "dry edge". This method is exemplified in U.S. Pat. No. 3,672,371, issued on June 27, 1972 to R. J. Roeder and in U.S. Pat. No. 3,881,490, issued on May 6, 1975 to H. A. Whitehead and R. V. Braun. In both these instances, the adhesive element does not extend the full longitudinal length of the product, but instead ends some distance therefrom. On the other hand, the adhesive element is covered by a protective strip which extends beyond the ends of the adhesive element. Accordingly, prior to use the ends of the release strip are not adhered to the adhesive and are free to be gripped for removal. In use, the end portions of the product are not adhered to the garment but instead, are also free to be gripped for removal. While these unadhered ends do in fact allow for easier peeling of both the release strip prior to use and of the product from the undergarment during use, there are drawbacks. The release strip is generally stiffer than the remainder of the product and so the unadhered ends of the strip tend to stand away from the product and tend to "catch" on each other so that the product cannot be easily handled during production and packaging. This problem is particularly acute in the products such as the so-called three-dimensional curved garment liners as are described in a commonly assigned U.S. patent application having a serial number yet to be determined. The curvature of these napkins causes the stiffer release strip material to stand away even further. During use, the unadhered ends of the product provide a starting point for the undesirable detachment and displacement of the entire product under the forces exerted by body and garment movements.
It can thus be seen that, prior art efforts notwithstanding, a completely satisfactory solution to the apparently conflicting criteria in-use tenacity and easy peelability has heretofore been unavailable.